Understanding virtual machines: Part one

Virtual machine operation was long considered a more advanced information technology topic. Increasingly though, the topic is taking its place among the many initial things to learn in the IT field because VM use is exploding.

To understand VMs, first understand computers typically run only one operating system. Users are free to run as many applications desired, but nearly all computers have only one operating system which is fine under most conditions. But, consider a condition where a certain application is needed, we have it, but the operating system on the PC does not support it.

This is a common problem in business when new computers replace older ones, but a very important application installed on an older PC is still needed to perform a business-critical role. One option is to load an old operating system on the new PC. Another solution is to run a virtual machine - actually a system virtual machine - which is defined as any entity that provides a complete system platform that supports the execution of an operating system. In other words, it is a program that creates the environment for other operating systems to run.

Virtual machines can emulate both new and old operating systems. They allow the option to do something like run a Linux operating system on a Windows PC. Normally, the user would have to load Linux as the operating system (or dual-boot) to use it, but the VM running as an application on the Windows PC creates the environment where Linux thinks it is the only operating system running. Two types of VMs include those that run as an application on a host operating system along with those that do not need a host OS.

Next week, we look at an example of each and discuss the advantages/disadvantages.

Ron Poland is a professor in the Computer Information Systems AAS program at Clinton Community College. Poland is certified in company repair and networking by the Computer Technology Industry Association (CompTIA). He is also a Cisco certified network assistant. Questions may be sent to him via e-mail at ron@ronpoland.com.

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